The present invention relates to a dental composite material of the type useful in tooth restorations and the like, such as for example, as an alternative to a conventional dental amalgam or composite. More specifically, the invention relates to such a material having a hardenable matrix component and a filler component. Specifically, the invention relates to such a material wherein said filler component includes fillers having three different particle sizes. A method according to the invention includes compacting a dental composite material into a prepared tooth cavity, wherein the material has a packability index above about 300 g/mm2.
Certain practical considerations apply to the formulation and application of dental restorative, such as resin-based posterior dental restoratives. Accordingly, it is greatly preferred that the restorative composition be effectively homogeneous such that air bubbles or structural discontinuities are substantially avoided from introduction into the tooth structure. Additionally, it is preferred that such materials be xe2x80x9cpackablexe2x80x9d or xe2x80x9ccondensablexe2x80x9d and be capable of deforming a matrix band during the course of tooth filling. Such materials should also be capable of withstanding the physical stresses extant in the posterior region of the mouth and not crumble, fracture or erode under such conditions.
It has long been known to employ metallic amalgams in the restorations of posterior teeth. Such amalgam materials have been shown to have good resistance to the physical stresses experienced by posterior teeth and to posses small coefficients of thermal expansion. Such amalgams have also been demonstrated to have good xe2x80x9cpackabilityxe2x80x9d and to demonstrate other properties necessary of the posterior restorative. Such materials however, suffer from uncertainty as to the biological effect of the introduction of mercury and other materials in the oral cavity over long periods of time.
Those skilled in the art of dental restoration will appreciate that certain posterior restorations, such as Class II restorations, require the employment of a matrix for proper application. This is to ensure that the replacement of the natural tooth structure is replaced and restored in close contact with the adjacent tooth. Thus, it will be appreciated that the use of a matrix band to surround the tooth to be repaired is generally necessary. Such bands are needed when the tooth to be repaired must be excavated in such a fashion that the resulting cavity preparation communicates from the top surface to one or more of the side surfaces of the tooth. In such a case, the matrix band is placed around the tooth and held tightly in place while a restorative material such as amalgam is put into place. A measure of a material""s packability and values of the measured packability for conventional dental amalgams is described for example in U.S. Pat. No. 4,226,622 which is hereby incorporated by reference for such disclosure. Heretofore, conventionally and commercially available composite materials, while durable, have suffered from low packability values. This results in less than effective distention of the matrix band, often resulting in xe2x80x9creboundxe2x80x9d or recovery of the band""s original shape and ultimately to less than ideal contacts. A need exists therefore for a durable posterior dental composite material which has high packability.
It is an object of the present invention to provide a dental composite material.
It is another object of the present invention to provide a composite material as above, which is highly packable.
It is a further object of the present invention to provide such a composite material which is durable when used in dental restorations.
It is still another object of the invention to provide an alternative dental material to conventional amalgams and composites.
It is yet another object of the invention to provide a dental restorative material that can be placed where desired and then sculpted or carved for aesthetics.
These and other objects of the present invention which should become apparent from the description to follow, are carried out by the invention as hereinafter described and claimed.
In general, a dental composite material comprises a hardenable resin or compomer matrix and a filler component. The filler component comprises (a) a first plurality of glass particles having an average particle size of from about 1 to about 10 micrometers; (b) a second plurality of glass particles having an average particle size of from about 0.1 to about 1 micrometers; and, (c) a plurality of filler particles having an average particle size of from about 0.01 to about 0.04 micrometers. One embodiment of the invention comprises from about 12 to about 25 percent by weight of said resin matrix and from about 75 to about 88 percent by weight of said filler component.
A method according to the present invention for restoration of a tooth includes selecting a tooth in need of restoration, the tooth having an original conformation having at least a top surface and a side surface. A portion of the tooth is removed to form a cavity preparation. The cavity preparation may communicate from the top to surface to at least a first side surface of the tooth. At least the first side surface is surrounded with a matrix band substantially completely covering the cavity where it communicates with the first side surface. A dental composite material according to the invention, as discussed above and preferably having a packability index above about 300 g/mm2, is applied to the cavity. The dental composite material is compacted to deform the matrix band, and the material is hardened, preferably by exposure to actinic light. The original conformation of the tooth is thereby substantially restored.